<!doctype html>
<html lang="zh-cn">
<head>
  <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
  <meta name="viewport" content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <title>:not排除最后一个元素</title>
</head>
<style>
  ul {
    margin: 50px auto;
    width: 400px;
    height: 48px;
    font-size: 24px;
    display: flex;
    flex-direction: row;
    list-style: none;
  }

  ul li {
    width: 100px;
    line-height: 48px;
    text-align: center;
  }

  ul li:not(:last-child) {
    border-right: 1px solid #666;
  }
</style>
<body>
<ul>
  <li>右边框</li>
  <li>右边框</li>
  <li>右边框</li>
  <li>右边框</li>
</ul>
</body>
</html>
